Cooling jacket construction



`luly 5, 1938. R. H. GODDARD COOLING JACKET CONSTRUCTION` Filed March 10, 1937 llllllllfllllllllilll.

\ I 1 v wvl/lll Patented July 5, 1938'.

1mm-t 11. Godano. unwell, N. Mex.

Appumun Maren' 1o, 1931, semi No. 130,144

1o claims. (01122-361) This invention relates to the cooling of the outerl wall of a combustion chamber or other highly heated container. It is the general object of my invention to provide an improved cooling jacket construction by which such chambers or containers may be very effectively cooled by a jacket structure of minimum weight.

To the attainment of this object, I provide ai system of conduits or .tubes and associated parts, by which a cooling fluid may be circulated about a combustion chamber and by which the transfer of heat thereto may be facilitated.

More speciilcally, I provide conduits or tubes of l5 such cross section as to present maximum resistance to distortion, together with associated heat transfer elements or iiller strips which overcome the disadvantage of line contact only between such a conduit and a combustion chamber wall. 20 My invention further relates to arrangements and combinations of parts which will be hereinafter described and `more particularly pointed out in the appended claims. Preferred forms of the invention are shown in 26 the drawing, in which- Flg. 1 is a partial sectional elevation showing my improved cooling jacket construction applied to the cylindrical wall of a combustion chamber;

Figs. 2, 3, 4 and 5 are sectional elevations of 30 modified forms of filler strips;

Fig. 6 is a view similar to Fig. 1 but showing a modified construction; and

Fig. 'l is a similar view of a further modication.

Referring to Fig. 1, I have shown a portion of a 35 combustion chamber C having a side wall I0. A

cooling conduit or tube II is maintained in cony tact with the outer surface of the chamber wall v Ill. The tube II is commonly wound in helical formation around the cylindrical chamber but may 40 be placed lengthwise of the chamber if so desired. I form the conduits or tubes II of relatively thin metal, usually copper, and I preferably form the tubes of circular cross section, as tubes of this section have maximum resistance to distortion by 45 either internal or external force. Y

'Any suitable cooling liquid may be circulated through the tubes I I, and this liquid under certain conditions will be at substantial pressure.

Each tu e II makes line contact only with the Wall I Il, w ich is a most unfavorable condition for heat transfer. Accordingly Iprovide filler strips I2 to improve the thermal conductivity. The strips I2 may be of copper or copper alloy of such 55 composition that it will not be melted by the heat .transferred from the highly heated chamber wall I0.

The strip I 2 in Fig. l is substantially triangular in cross section, with curved outer faces adapted to closely engage the outer surfaces of adjacent tubes I I. With this construction, heat will be transferred continuously from all portions of the combustion chamber wall, either through direct contact with the tubes II or indirectly through the illler strips I2.

In applying my improved jacket construction to a combustion chamber, I ilnd it desirable to ilrst wind a continuous triangular illler strip in helical- ,formation around the combustion chamber and to then wind a continuous tube II in the helical recesses formed between adjacent tlller strips.

Instead of the sharply triangular filler strip shown in Fig. l, I may provide a 1111er strip I4 having rounded edges as indicated in Fig. 2, such a strip being easier to manufacture and easier to manipulate, but being slightly less eilicient as to heat transfer, as the air spaces between tubes are not entirely illled.

In Fig. 3 I have shown a filler strip I5 of laminated structure, which may be formed by winding successive layers. of decreasing width around the combustion chamber wall. For relatively large chambers and conduits, such a laminated construction has structural advantages.

In Fig. 4 I have indicated a further modified form of filler strip IB in which a longitudinal passage I1 is provided. With this construction, the strip I6 forms in eiect an additlonalcontinuous conduit through which also cooling iluid may be circulated. y

In Fig. 5 I have shown a form of filler strip comprising an inner band I8 and an outer triangular portion I9. In this construction, the band I8 is preferablyof copper to resist the high temperature of the combustion chamber wall, while the l portion I9 may be of aluminum. This construction is desirable where lightness is important, as aluminum at high temperature is substantially equal to copper in thermal conductivity, whereas the weight of aluminum is only about one-third that of copper for equal mass.

In order to still further facilitate heat transfer and also to provide increased strengthlmay provide additional iiller strips 20 (Fig. 1) outside of the conduits or tubes I-I and enclosed by a strong outer casing 2l. The filler strips 20, being substantially removed from the combustion chamber wall, are exposed to less intense heat and may be of aluminum, with the advantages previously described. The outer casing 2i may be of strong each strip is formed of a copper portion 2l and an aluminum portion 25, somewhat as shown in Fig. 5 but having the copper portion 24 of such varied thickness that its outer surface at all points will be at substantially the same temperature, which temperature is safely below the melting point of aluminum.

The outer filler strips 20 may also be used to advantage without using the outer casing 2| where only moderate pressures will be developed.

It will be noted that where the copper portion is more Widely spaced from the cooling tubes H, the thickness of the copper is increased to offset the decreased cooling effect of the uid in the tubes.

Where cooling iluid and -particularly a liquid is circulated at a fairly rapid rate through the cooling tubes, it is found that the warmer portion of the liquid circulates adjacent the combustion chamber wall I0, while the cooler portion of the liquid is displaced outward away from the wall I0 by centrifugal force. Also if the liquid should become heated to such an extent that it began to boil, the liquid portion would be thrown to the outside of the tube and would of course be a much better heat conductor than the warm vapor. Furthermore, the reduced amount of metal at the point a in Fig. 1 greatly reduces the heat transfer to the outer filler strips 20 from which heat could be transferred to the Ycooler outer portion of the liquid. To overcome these disadvantages, I may utilize one of the constructions shown in Figs. 6 and '7.

In Fig. 6 I have shown the tubes Il provided with lining strips 30 at the .top and both sides of each tube, these strips being preferably continuous and formed of aluminum. The addition of the strips 30 provides a substantial thickness of metal at the line 6-6 (Fig. 6) and facilitates transfer of heat to the outer portion of the jacket structure and to the cooler portion of the liquid in the tubes II.

In Fig. 'I I have shown a slight modification of this construction, in which a one-piece reenforcing lining member 35 of substantially U- shaped section is provided, this member also being preferably formed of aluminum. 'I'his onepiece construction is more readily assembled with the tubes and stiiens and reenforces the tubes to a substantial extent.

It will be understood that the lining strips 30 and lining members 35 may be inserted in any of the tubes I i and may be used in combination with any of the lier strips shown in any one of Figs. 1 to 7.

A cooling jacket as above described hasv been found extremely eiilcient and satisfactory where high temperatures are encountered and where light weight combined with high tensile strength is essential. -Such conditions obtain in the construction of rocket motors for aeronautical puirposes, where combustion chambers of very thin sheel steel must function under extremely high temperature conditions.

arcani My improved cooling jacket construction not only provides effective cooling but also directly reenforces and strengthens the thin combustion chamber walls. Where the -outer casing 2l is used, this outer casing, being relatively cool, may be of high tensile strength while the combustion chamber wall may. be of a metal which is highly heat conductive but without special strength qualifications.

While my new construction is most eiiicient when using a liquid cooling medium, many of the advantages will be retained when using a gas or vapor under high pressure, or a mixture of liquid and gas or vapor.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claimv is:-

1. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, that improvement which consists in providing for said wall a cooling jacket construction comprising abutting circular fluidconducting tubes directly engaging said wall, and separate heat-conducting metal filling strips engaging said wall and disposed between adjacent tubes and in close contact therewith, said strips a thin sheet metal wall, that improvement which V consists in.providing for said wall a cooling jacket construction comprising circular fluid-conducting tubes directly engaging said wall, and separate heat-conducting metal lling strips engaging said wall and disposed between adjacent tubes and in close contact therewith, said strips having a substantially triangular cross section closely filling the spaces between said tubes and said wall and being formed of a plurality of circumferentially superposed laminated layers.

3. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, that improvement which consists in providing for said wall a cooling jacket construction comprising circular fluid-conducting tubes directly engaging said wall, and separate heat-conducting metal filling strips engaging said wall and disposed between adjacent tubes and in stantially triangular cross section closely iilling the spaces between said tubes and said wall and being formed of an inner wall-engaging portion of copper and a superposed outer portion of aluminum.

4. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, that improvement which consists in providing for said wall a cooling jacket construction comprising circular fluid-conducting tubes directly engaging said wall, and separate heat-conducting metal filling strips engaging said wall and disposed between adjacent tubes and in close contact therewith, said strips having a substantially triangular cross section closely ifiiling the spaces between said tubes and said external surface.

5. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, the combination with said wall of a cooling jacket construction comprising thin huid-conducting tubes engaging said wall, a copper iiller strip engaging said wall and disposed between adjacent tubes and .in contact therewith, aluminum outer filler strips mounted between the outer portions of adjacent tubes and in contact therewith and with said copper strip, and a steel casing enclosing said tubes and outer ller strips.

6. In combustion apparatus wherein high temperaturesare developed within a chamber having a thin metal wall, the combination with said wall of a cooling jacket construction comprising thin fluid-conducting tubes engaging said wall and a substantially triangular metal ller strip disposed between and in continuous contact with said wall and adjacent tubes, said strip having a continuous longitudinal passage therethrough effective to conduct additional cooling iluid about said chamber.

7. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, the combination with said wall of a cooling jacketconstruction comprising thin huid-conducting tubes engaging said wall, separate heat-conducting ller strips engaging said wall and disposed between adjacent tubes and in contact therewith, and additional separate heat-conducting ller strips disposed between the outer portions of adjacent tubes.

8. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, that improvement which consists in providing a helical tubular cooling coil closely engaging said wall, and a shaped helical metal winding strip interposed between the turns of said coil and contacting said wall and turns and substantially filling the spaces between said wall and turns.

9. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, that improvement which consists in providing a helical tubular cooling coil closely engaging said wall, a shaped helical metal winding strip interposed between the turns I of said coil and contacting said wall and turns and substantially iilling the spaces between said wall and turns, and an aluminum lining for said tube on portions remote from said wall.

10. In combustion apparatus wherein high temperatures are developed within a chamber having a thin sheet metal wall, that improvement which consists in providing a helical tubular cooling coil closely engaging said wall, a shaped helical metal winding strip interposed between the turns of said coil and contacting said wall and turns and substantially illling the spaces between said wall and turns, and a one-piece aluminum lining for said tube which is U-shaped in section and covers the sides thereof and the portion remote from saidwall.

ROBERT H. GODDARD. 

